KVM: VMX: Stuff vcpu->arch.apic_base directly at vCPU RESET

Write vcpu->arch.apic_base directly instead of bouncing through
kvm_set_apic_base().  This is a glorified nop, and is a step towards
cleaning up the mess that is local APIC creation.

When using an in-kernel APIC, kvm_create_lapic() explicitly sets
vcpu->arch.apic_base to MSR_IA32_APICBASE_ENABLE to avoid its own
kvm_lapic_set_base() call in kvm_lapic_reset() from triggering state
changes.  That call during RESET exists purely to set apic->base_address
to the default base value.  As a result, by the time VMX gets control,
the only missing piece is the BSP bit being set for the reset BSP.

For a userspace APIC, there are no side effects to process (for the APIC).

In both cases, the call to kvm_update_cpuid_runtime() is a nop because
the vCPU hasn't yet been exposed to userspace, i.e. there can't be any
CPUID entries.

No functional change intended.

Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210713163324.627647-17-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 207393a429d1b9dbc5e9129cc85e7a3b757f25a8..2fc232e1bc2086100156625f90bc5112af4fb4e5 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4391,7 +4391,6 @@ static void init_vmcs(struct vcpu_vmx *vmx)
 static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 {
        struct vcpu_vmx *vmx = to_vmx(vcpu);
-       struct msr_data apic_base_msr;
        u32 eax, dummy;
        u64 cr0;
 
@@ -4409,12 +4408,10 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
        kvm_set_cr8(vcpu, 0);
 
        if (!init_event) {
-               apic_base_msr.data = APIC_DEFAULT_PHYS_BASE |
-                                    MSR_IA32_APICBASE_ENABLE;
+               vcpu->arch.apic_base = APIC_DEFAULT_PHYS_BASE |
+                                      MSR_IA32_APICBASE_ENABLE;
                if (kvm_vcpu_is_reset_bsp(vcpu))
-                       apic_base_msr.data |= MSR_IA32_APICBASE_BSP;
-               apic_base_msr.host_initiated = true;
-               kvm_set_apic_base(vcpu, &apic_base_msr);
+                       vcpu->arch.apic_base |= MSR_IA32_APICBASE_BSP;
        }
 
        vmx_segment_cache_clear(vmx);